(19)
(11) EP 0 208 159 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
25.10.1989 Bulletin 1989/43

(43) Date of publication A2:
14.01.1987 Bulletin 1987/03

(21) Application number: 86108003.4

(22) Date of filing: 12.06.1986
(51) International Patent Classification (IPC)4: B29D 11/00, G02B 6/04
(84) Designated Contracting States:
DE FR GB NL

(30) Priority: 12.06.1985 JP 127553/85
18.06.1985 JP 130837/85
19.06.1985 JP 131976/85
15.11.1985 JP 256164/85

(71) Applicant: MITSUBISHI RAYON CO., LTD.
Tokyo 104 (JP)

(72) Inventors:
  • Yamamoto, Takashi
    Saiki-gun Hiroshima, 739-04 (JP)
  • Mishina, Yoshihiko
    Otake-shi Hiroshima, 739-06 (JP)
  • Oda, Masaaki
    Otake-shi Hiroshima, 739-06 (JP)

(74) Representative: Abitz, Walter, Dr.-Ing. et al
Patentanwälte Abitz & Partner Postfach 86 01 09
81628 München
81628 München (DE)


(56) References cited: : 
   
       


    (54) Process for Producing an optical Transmission Medium


    (57) The graded-index optical transmission medium with a low transmission loss, a favorable index distribution and superior in softness etc. can be constituted by a mixture of polymers Pn having different refractive indices and by restricting the attenuation LF of the medium in accordance with the following inequality (I).
    The medium may advantageously be produced by way of admixing a thermoplastic polymer (A) and a monomer (B) able to form a polymer mutually soluble with the polymer (A), molding the mixture and volatilizing the monomer (B) from the surface of thus shaped substance.

    wherein Wn are the respective proportions by weight of mixing of the polymers Pn to the whole of the mixture of the N polymers Pn, and Σ Wn is equal to one. n=1






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